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The effect of offsite construction on occupational health and safetyMcKay, Lawrence J. January 2010 (has links)
The continuous desire to improve health and safety in UK construction has in recent years been challenged to adopt offsite strategies in order to address the poor health and safety record of construction. Despite the benefits of using offsite there has been little research on the actual benefits and disadvantages of the effect of offsite on occupational health and safety. This is important given that the UK government has promoted the use of offsite to improve health and safety performance. This thesis provides a strategy for the management of offsite risk and a risk management tool has been developed. The study investigated offsite manufacturers views on offsite activities and risks in comparison with insitu activities and risks. This was achieved through three phases: phase I comprised two expert group interviews, phase II involved ergonomic audits and phase III consisted of three semi-structured interviews with three offsite manufacturers. The thesis identified that there are significant health and safety benefits of offsite. The benefits relate to specific activities within the offsite categories and context studied. Examples include the elimination of work at height, reduction in noise, reduction in work in confined space, reduction in congested work with trade overlap and greater control over work in the factory. The research revealed that there are still potential health and safety risks with offsite. Examples include; transportation and delivery of units of large size and weight with associated high consequence craneage and handling risks (unit fall and hand injury), whole body vibration, cuts, MSDs, RSIs, fumes and slips trips and falls. There appears to be little in the literature to support the identification of offsite risk issues. The study identified strategies to eliminate and reduce offsite residual risks. The case study investigated solutions to further reduce residual risks, which were further explored in phase III the semi-structured interviews. The solutions are grouped into four approaches: process change, workplace environment designing out risks, automation and the use of tools. An offsite risk management tool was developed which transfers knowledge from the study to provide awareness and management of offsite risk. The thesis provides a contribution to knowledge by providing a better understanding of offsite risks, offsite residual risks and strategies used to reduce residual risks.
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Pós-secagem natural de lodos de estações de tratamento de água e esgoto sanitários. / Post drying of residues generated in water wastewater treatment plants by natural processes.Souza, Weverton Gesiel de 18 September 2012 (has links)
Os processos de secagem de resíduos produzidos em estações de tratamento de água e esgoto por processos mecânicos podem gerar lodos com teores de sólidos de 20% a 30%, podendo estes variar de acordo com as características do lodo bem como da tecnologia de desidratação. Uma vez que os custos de transporte e disposição final têm aumentado de forma significativa para lodos produzidos em regiões metropolitanas, torna-se atrativo a sua redução mediante o aumento do teor de sólidos do lodo desidratado. Desta forma, este trabalho teve por objetivo avaliar o processo de pós-secagem de resíduos gerados em estações de tratamento de água (ETA) e esgoto (ETE) por processos naturais, tendo-se avaliado a influência das condições climáticas da cidade de São Paulo para diferentes estações do ano. O estudo foi realizado com dois tipos de leitos de secagem em escala piloto; leito coberto (LC) e leito aberto (LA), tendo os mesmos 1,80m2 de área e piso impermeabilizado. Os dados hidrometeorológicos foram obtidos mediante a operação de uma estação hidrometeorológica portátil que forneceu dados de temperatura do ar e do lodo, umidade relativa do ar, radiação solar global, velocidade do vento e precipitação. O lodo gerado nas estações de tratamento foram dispostos nos leitos de secagem em leiras com 30cm de altura, sendo revolvidos e realizadas análises de teor de sólidos do lodo três vezes por semana, o período de secagem de cada ciclo foi de 30 dias. Os teores de sólidos dos lodos obtidos nos ensaios com pós-secagem natural apresentaram resultados distintos para diferentes períodos do ano; durante o período do verão foi obtido lodo com teor de sólido final de 58% médio, enquanto, no período de inverno foi obtido lodo com teor de sólido final de 18% médio. Foi utilizado um modelo matemático para o processo de secagem do lodo utilizando os dados meteorológicos medidos, uma equação do balanço de calor foi aplicada para o volume de controle do leito de secagem do lodo considerando a transferência de calor por radiação, convecção, e evaporação. / The mechanical drying process of residuals produced in water and wastewater treatment plants can generate sludge with solids content of 20% to 30%. These values may vary according to the characteristics of the sludge and dehydration technology. The costs of sludge produced in metropolitan areas have increased significantly due to transportation and final disposal. Hence, it is to, becoming attractive to reduce the residue volume by increasing the solids content of the dewatered sludge. This study aimed to evaluate the process of post drying of residues generated in water wastewater treatment plants (WTP and WWTP) by natural processes, evaluating the influence seasonal variation of the weather in the São Paulo city. The study was conducted with two drying beds on a pilot scale; one being a cover unit (CU) and the other an uncover unit (UU). Both units have the same area of 1.80m2 and waterproof floor. The hydrometeorological data were obtained through the operation of a weather station installed close to the units that supplied data for temperature of the air and sludge, relative humidity, solar radiation, wind speed and precipitation. The sludge source in the treatment stations are arranged in the drying beds to ridges with 30cm height, the sludge was mixed and analyzed of solid content three times a week, the drying time of each cycle was 30 days. The solid content of the sludge obtained in tests with post drying by natural processes showed different results for different seasonal of the year and during the summer period was obtained sludge with solid content finale average of 58%, while in the winter was obtained sludge with solid content finale average of 18%. A mathematical model is developed for the process of drying of sludge, a heat-balance equation is applied for a control volume of sludge that takes into account the heat transfer by radiation, convection, and evaporation.
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Pós-secagem natural de lodos de estações de tratamento de água e esgoto sanitários. / Post drying of residues generated in water wastewater treatment plants by natural processes.Weverton Gesiel de Souza 18 September 2012 (has links)
Os processos de secagem de resíduos produzidos em estações de tratamento de água e esgoto por processos mecânicos podem gerar lodos com teores de sólidos de 20% a 30%, podendo estes variar de acordo com as características do lodo bem como da tecnologia de desidratação. Uma vez que os custos de transporte e disposição final têm aumentado de forma significativa para lodos produzidos em regiões metropolitanas, torna-se atrativo a sua redução mediante o aumento do teor de sólidos do lodo desidratado. Desta forma, este trabalho teve por objetivo avaliar o processo de pós-secagem de resíduos gerados em estações de tratamento de água (ETA) e esgoto (ETE) por processos naturais, tendo-se avaliado a influência das condições climáticas da cidade de São Paulo para diferentes estações do ano. O estudo foi realizado com dois tipos de leitos de secagem em escala piloto; leito coberto (LC) e leito aberto (LA), tendo os mesmos 1,80m2 de área e piso impermeabilizado. Os dados hidrometeorológicos foram obtidos mediante a operação de uma estação hidrometeorológica portátil que forneceu dados de temperatura do ar e do lodo, umidade relativa do ar, radiação solar global, velocidade do vento e precipitação. O lodo gerado nas estações de tratamento foram dispostos nos leitos de secagem em leiras com 30cm de altura, sendo revolvidos e realizadas análises de teor de sólidos do lodo três vezes por semana, o período de secagem de cada ciclo foi de 30 dias. Os teores de sólidos dos lodos obtidos nos ensaios com pós-secagem natural apresentaram resultados distintos para diferentes períodos do ano; durante o período do verão foi obtido lodo com teor de sólido final de 58% médio, enquanto, no período de inverno foi obtido lodo com teor de sólido final de 18% médio. Foi utilizado um modelo matemático para o processo de secagem do lodo utilizando os dados meteorológicos medidos, uma equação do balanço de calor foi aplicada para o volume de controle do leito de secagem do lodo considerando a transferência de calor por radiação, convecção, e evaporação. / The mechanical drying process of residuals produced in water and wastewater treatment plants can generate sludge with solids content of 20% to 30%. These values may vary according to the characteristics of the sludge and dehydration technology. The costs of sludge produced in metropolitan areas have increased significantly due to transportation and final disposal. Hence, it is to, becoming attractive to reduce the residue volume by increasing the solids content of the dewatered sludge. This study aimed to evaluate the process of post drying of residues generated in water wastewater treatment plants (WTP and WWTP) by natural processes, evaluating the influence seasonal variation of the weather in the São Paulo city. The study was conducted with two drying beds on a pilot scale; one being a cover unit (CU) and the other an uncover unit (UU). Both units have the same area of 1.80m2 and waterproof floor. The hydrometeorological data were obtained through the operation of a weather station installed close to the units that supplied data for temperature of the air and sludge, relative humidity, solar radiation, wind speed and precipitation. The sludge source in the treatment stations are arranged in the drying beds to ridges with 30cm height, the sludge was mixed and analyzed of solid content three times a week, the drying time of each cycle was 30 days. The solid content of the sludge obtained in tests with post drying by natural processes showed different results for different seasonal of the year and during the summer period was obtained sludge with solid content finale average of 58%, while in the winter was obtained sludge with solid content finale average of 18%. A mathematical model is developed for the process of drying of sludge, a heat-balance equation is applied for a control volume of sludge that takes into account the heat transfer by radiation, convection, and evaporation.
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